Limiting plant growth with heterocyclic alkylthiocyanate and isothiocyanate

ABSTRACT

Plant growth limiting compositions and methods of limiting vegetative growth with non-phytotoxic concentrations using certain alkylthiocyanates and isothiocyanates.

O Unified StfiiQS Patent [1 1 1111 3,725,@3

Newallis et ai. 1 1 Apr. 3, 1973 [54] LIMITING PLANT GROWTH WITH [56]References Cited HETEROCYCLIC ISOTHIOCYANATE 2,946,720 7 1960 Lewis..424/285 2,394,915 2 1946 Jones ..71 104 [751 Inventors Peter f2,642,353 6 1953 Mowry etal. ..71 104 f 3,553,243 1/1971 Hein ..71/104Elma", Frame 2,929,702 3/1960 Speziale ..71/88 Ram 3,393,209 7/1968Majewski ..71/88 [73] Assignee: Chemagro Corporation, Kansas FOREIGNPATENTS 0R APPLICATIONS City, Mo. [22] Filed: N0 20, 1970 539,263 4/1957Canada ..71 76 [21] Appl. No.: 91,541 Primary Examiner-Lewis Gotts 1Assistant ExaminerG. Hollrah 52 us. 131. ..71/76, 71/73, 71/74,Ammekaurgess Dinklage & Sprung 7l/75,71/88,7l/90,71/9l,7l/94,7l/95,

71/96, 260/294.8 E, 260/294.8 G, 1 ABSTRACT 260/32612 R 260/32691260/329R Plant growth limiting compositions and methods of260/3321260/3325,(l/345142605461 limiting vegetative growth withnon-ph'ytotoxiecon- 260/3462 centrations using certain alkylthiocyanatesand [51] Int. Cl. ..A0ln 5/00 isothiocyanates [58] Field of Search..71/76, 104,88

5 Claims, No Drawings LIMITING PLANT GROWTII WITH HETEROCYCLICALKYLTHIOCYANATE AND ISOTHIOCYANATE It has been found in accordance withthe present invention that the particular heterocyclic alkylthiocyanates and heterocyclic alkyl isothiocyanates of the formulas:

wherein:

R and R are each individually hydrogen or alkyl, and

Z is furyl, dihydrofuryl, tetrahydrofuryl, benzofuryl, pyranyl,dihydropyranyl, tetrahydropyranyl, thienyl, pyridyl, pyrrolyl, picolyl,indolyl, dihydrothienyl-l oxide, dihydrothienyl-l, l-dioxide ortetrahydrothienyl-l-dioxide as well as alkyl, chloro, bromo, and nitrosubstitution products thereof, alkyl in all instances containing fromone to five carbon atoms.

The present invention relates to and has for its objects the use asplant growth regulators, of certain heterocyclic (alkyl thiocyanates)and isothiocyanates, some of which are known as nematocides andflavoring agents, in the form of mixtures of such compounds in a new wayespecially for regulating the growth of vegetation with other andfurther objects becoming apparent from a study of the withinspecification.

It is known that some of the heterocyclic alkyl isothiocyanates of thisinvention can be used for the control of parasitic worms such asnematodes (U.S. Pat. No. 2,946,720) and as flavoring agents for food andbeverages (U.S. Pat. No. 2,905,701 Other reports describing some of thecompounds of this instant invention can be found in the followingreferences: J. Am. Chem. Soc. 51, 3131 (1920); Bull. Chem. Soc. Japan33, 1465 (1960); Anne 445, 201 (1925); Bull Chem. Soc. Japan36,108(1963).

It has been found that in accordance with the present invention, theparticular heterocyclic alkyl thiocyanates and heterocyclic alkylisothiocyanates of the formulas:

wherein:

R and R are each individually hydrogen or alkyl and Z is furyl,dihydrofuryl, tetrahydrofuryl, benzofuryl, pyranyl, dihydropyranyl,tetrahydropyranyl, thienyl, pyridyl, pyrrolyl, picolyl, indolyl,dihydrothienyll -oxide dihydrothienyl-l, l-dioxide ortetrahydrothienyl-ldioxide as well as alkyl, chloro, bromo, and nitrosubstitution products thereof, alkyl in all instances containing fromone to five carbon atoms, possess plant growth-regulating properties.

It is very surprising then that some of the heterocyclic alkylthiocyanates and heterocyclic alkyl isothiocyanates which are known asnematocides are also usable according to the present invention, having ahigh degree of growth regulating activity as well as a broad spectrum ofsuch activity. Some of these compounds may be used in a new way forstunting the growth of monocotolydonous and dicotolydonous crop and weedplants, ornamentals, shrubs and trees. Selected compounds of thisinvention have a beneficial effect on crops such as soybeans andsnapbeans by increasing the yield and/or protein content of such plants.Both alone and in synergistic combinations with maleic hydrazide, thecompounds of this invention retard the growth of grasses and reduce thephytotoxic effects of maleic hydrazide when used alone at comparablerates. Some of the compounds of this invention can cause the formationof abscission layers of fruit or buds, so that the number of buds orfruit dropping from a plant and/or the ease of the dropping of suchfruit may be regulated. Other types of beneficial effects on certainplants may be anticipated from the above described biological effects.These include the regulation of the setting of fruit of spermatophyticplants, increasing the resistance of plants to frost or drought damage,increasing the yield of sugar beets or cane, and their sugar content,causing defoliation of cotton with or without addition of commercialdefoliants such as S,S,S,-tributyl phosphorotrithioate (DEF) orS,S,S,-tributyl phosphorotrithioite (FOLEX), and increasing the size offlowers and shape of ornamental plants, reduction of the undesirablegrowth of suckers for plants such as tobacco, inhibition of thesprouting of potatoes and breaking plant dormancy and similar suchbiological effects.

Since the known commercial plant growth regulators are generally membersof chemical classes such as phosphonium and ammonium salts, amides orcarbox- 'ylic acids, it was surprising that selected members from theclasses set forth herein would exhibit a high degree of plant growthregulant activity. Furthermore, it was even more surprising to find thata few selected compounds of this class were outstandingly active, forexample, tetrahydrofurfuryl isothiocyanate. It was further found thatselected compounds from the classes when tested under field conditionsproduced not only desirable modifications in plant growth but economicbenefits, such as yield increases. Thus, the active compounds of thisinvention represent a valuable enrichment of the art.

As examples of heterocyclic alkylthiocyanates and isothiocyanates whichcan be used according to this instant invention, the following compoundsmay be cited in particular:

(1 2-Tetrahydrofurfuryl isothiocyanate (2) Z-Furfuryl isothiocyanate 32-lsothiocyanato-3 ,4-dihydro-2I-I-pyran (6) 2-Thenyl isothiocyanate (7)5-Chloro-2-thenyl isothiocyanate l0) 2-Thenyl thiocyanate l l)5-Chloro-2-Thenyl thiocyanate l2) 5-Bromo-2-thenyl thiocyanate l 3)3-Thiocyanatomethyl 2,5-dihydrothiophene 1,1-dioxide 15)2-5-Dichloro-3-thenyl thiocyanate l7) 5-Methyl2-thenyl thiocyanate l8)2-(2-Furyl)-ethyl isothiocyanate 19) l-( 2-Furyl)-ethyl isothiocyanate(20) Z-Pyridylmethyl isothiocyanate (21 2-Benzofurfuryl isothiocyanate(22) 2-Tetrahydrofurfuryl thiocyanate (23) l-Methyl-2-pyrrolemethylisothiocyanate (24) 1 -M ethyl-2-indolemethyl isothiocyanate (25)6-Methyl-2-picolyl isothiocyanate (26) 2 ,5-Dichloro-3-thenylisothiocyanate (27) 2,5-Dibromo-3-thenyl isothiocyanate (28) 2,3,5-Trichloro-4-thenyl isothiocyanate (29) 2,5-Dimethyl-3-thenylisothiocyanate (30) S-Nitrofurfuryl isothiocyanate (312,3-Dihydro-2-furfuryl isothiocyanate (32) 3-thenyl thiocyanate (3 3)2,3-Dihydro-2-furfuryl isothiocyanate Some of the substances accordingto the present invention are new, although they can be manufacturedsimply by known methods. The compounds of this invention are obtained,for example, whenever the appropriate heterocyclic alkyl amine isreacted with carbon disulfide and a chloroformate at temperaturessubstantially between about -30 to +50C but preferably between l to 30Cin the presence of a base selected from the group of inorganic basessuch as sodium or potassium hydroxide or organic tertiary amines such aspyridine or triethylamine. With organic bases, it is optionallypreferred to use inert solvents such as chloroform or dioxane.

Alternatively, some of the new and old compounds can be prepared by theisomerization of the corresponding thiocyanate, by heating themoptionally in an inert solvent, preferably a dipolar aprotic solventsuch as dimethyl formamide, sulfolane, acetonitrile and the like attemperatures substantially between about 30 to 180C and optionally inthe presence of a Lewis acid catalyst such as zinc chloride, borontrifluoride and the like.

Advantageously, the active compounds according to the present inventionexhibit outstanding growth regulating properties with comparatively lowtoxicity to warm blooded creatures and concommittantly low phytotoxicityat the rates at which the compounds of this invention are applied.Hence, the instant compounds are suitable for use as plant growthregulating agents, for one or more of the above-mentioned purposes.

The active compounds according to the instant invention can be utilized,if desired, in the form of the usual formulations or compositions withdiluents or extenders, i.e., dispersible carrier vehicles, such assolutions, emulsions, suspensions, emulsifiable concentrates, spraypowders, pastes, soluble powders, dusting agents, granulates, etc. Theseare prepared in known manner, for instance by extending the activecompounds with dispersible liquid diluent carriers and/or dispersiblesolid carriers optionally with the use of carrier vehicle assistants,e.g., surface-active agents, including emulsifying agents and/ordispersing agents, whereby, for example, in the case where water is usedas diluent, organic solvents may be added as auxiliary solvents (ofAgricultural Chemicals, March 1960, pages 35-38). The following may bechiefly considered for use as carrier vehicles for this purpose:dispersible liquid diluent carriers, such as aromatic hydrocarbons(e.g., benzene, toluene, xylene, etc.), halogenated,

especially chlorinated, aromatic hydrocarbons (e.g., chlorobenzenes,etc.), paraffins (e.g., petroleum fractions), chlorinated aliphatichydrocarbons (e.g., methylene chloride, etc.), alcohols (e.g., methanol,ethanol, propanol, butanol, etc.), amines (e.g., ethanolamine, etc.),ethers, ether-alcohols (e.g., glycol monomethyl ether, etc.), amides(e.g., dimethyl formamide, etc.), sulfoxides (e.g., dimethyl sulfoxide,etc.), ketones (e.g., acetone, etc.), and water; as well as dispersiblefinely divided solid carriers, such as ground natural minerals e.g.,kaolins, alumina, silica, chalk, i.e., calcium carbonate, talc,kieselguhr, etc.) and ground synthetic minerals (e.g., highly dispersedsilic acid, silicates, e.g., alkali silicates, etc.); whereas thefollowing may be chiefly considered for use as carrier vehicleassistants, e.g., surface-active agents, for this purpose: emulsifyingagents, such as nonionic and anionic emulsifying agents (e.g.,polyethylene oxide esters of fatty acids, polyethylene oxide ethers offatty alcohols, alkyl sulfonates, aryl sulfonates, etc., and especiallyalkyl aryl-polyglycol ethers, magnesium stearate, sodium oleate, etc.),and dispersing agents, such as lignin, sulfite waste liquors, methylcellulose, etc.

Such active compounds may be employed alone or in the form of mixtureswith one another and/or with such solid or liquid dispersible carriervehicles and/or with other known compatible active agents, especiallyplant protection agents, such as fungicides, insecticides, bactericides,etc., if desired, or in the form of particular dosage preparations forspecific application made therefrom, such as solutions, emulsions,suspensions, powders, pastes, and granulates which are thus ready foruse.

As concerns commercially marketed preparations, these generallycontemplate carrier composition mixtures in which the active compound ispresent in an amount substantially between about 01-95 percent by weightof the mixture, whereas carrier composition mixtures suitable fordirection application or field application generally contemplate thosein which the ac-v tive compound is present in an amount substantiallybetween about 0.0l2.0 percent, preferably 0.0l-0.8 percent, by weight ofthe mixture. Thus, the present invention contemplates overallcompositions which comprise mixtures of a dispersible carrier vehiclesuch as (1) a dispersible carrier solid, or (2) a dispersible carrierliquid preferably including a carrier vehicle assistant, e.g.,surface-active agent, and an amount of the active compound which iseffective for the purpose in questions and in which is generally betweenabout 0.01- percent by weight of the mixture.

Furthermore, the present invention contemplates controlling the rate ofgrowth of plants, increasing their yield, protein content, sugarcontent, resistance to frost and drought damage or preventing the growthof undesirable suckers and other objects of this invention heretoforementioned by applying to one of (a) such plants and (b) their habitat,an efficacious amount of the particular active compound of the inventionalone or together with another active compound or with a carrier vehicleas noted above. The compounds of this invention can also be used tocontrol the size and shape of vegetative portions of ornamental plantsor their flowers. The instant formulations or compositions are appliedin the usual manner, for example, by spraying, atomizing, scattering,dusting, watering, sprinkling and the like either to the soil around theplants, to the plants themselves or both.

It will be realized, of course, that in connection with the use of thesecompounds for influencing the growth of plants and/or affecting theother desirable results heretofore mentioned, the concentration of theparticular-active compound utilized in the admixture with the carriervehicle will depend on the intended application and may be varied withina fairly wide range depending on weather conditions, the purpose forwhich the active compound is used and the plant species in which it isintended to produce the desired effect.

Therefore, in special cases it is possible to go above or below theafore-mentioned concentration ranges The following examples illustrate,without limitation,

the growth regulatory activity of the particular active compounds of thepresent invention.

Example I Cucumber Root Test Wettable powder base consisting of:

92 parts by weight hydrated silica (ultra fine, Hi-Si] 233) 4 parts byweight sodium lignin sulfonate Marasperse N") 4 parts by weightpolycondensate of ethylene oxide,

propylene oxide and propylene glycol (mol. wt. about 1000) (PluronicL-6l To produce a suitable preparation of the particular activecompound, 1 part by weight of such active compound is mixed intimatelywith 1 part by weight of the stated wettable powder base. To prepare a10,000 ppm. dilution, 0.4 grams of the resulting preparation isthoroughly mixed with 20 mls. of distilled water. The resulting dilutionis further diluted with distilled water to the indicated finalconcentrations. Whatman No. l

filter paper is placed in a 150 X 25 mm Petri dish, and 10 cucumberseeds are arranged on it in a row. The dish is then moistened with 7mls. of the specified dilution of the particular active compound.

Treated dishes are incubated in darkness at C.

Rating is determined on the basis of growth of the root during theperiod of 24 hours between the third and fourth day using average valuesfor the 10 seeds. 0" to 9 scale rating is used to indicate the activityof potential growth regulators. A 0 scale reading indicates growthretardation within the range of 0-10 percent when compared with thecontrol. A 9 scale reading corresponds to 90 percent or more growthretardation when compared with the control.

A (0) to (9) scale rating is used to indicate the activity of potentialgrowth promotants. (0) indicates growth promotion within the range of0-10 percent when compared with the control (9) indicates 90 percent orgreater growth promotion when compared with the control.

The particular active compounds tested, the concentration thereof usedand the results obtained can be seen from the following Table l.

TAB LE 1 Concentration (p.p.m.)

Active compound 10, 000 1, 000

CH:NC s O GH9NC s 0 CH=NO s O W CHaNC s CH2CH9NC S GH:NO s

c1 CHNC s Br- CH :NO s

9) men. 9 9 7 H-NC s 0 \s CH1S CN 01-- S 0111s CN Br 0112s ON 13 CHzS CN8 s 5 14 0111s CN 0 0 Brl lBr s 19 0111s CN 9 9 9 all [01 s (26) T lCHQNC s 9 9 9 CI L J01 i i-CHzS CN EXAMPLE ll Snap Bean Foliar SprayTest To produce a suitable preparation of the particular activecompound, 1 part by weight of such active compound is mixed intimatelywith 1 part by weight of the stated wettable powder base. To prepare a10,000 ppm. dilution, 0.8 grams of the resulting preparation isthoroughly mixed with 40 mls. of distilled water containing 0.01 percentpolyoxyethylene sorbitan monolaurate (Tween 20). The resulting dilutionis further diluted with distilled water to the indicated finalconcentrations.

Snap bean plants, as soon as the primary leaves are relatively smooth(6-7 days old) and are capable of absorbing and translocating chemicals,are sprayed with the given compound at the indicated concentration untiljust dew moist. For each test 40 mls. of the appropriate compounddilution are sprayed on four plants in an area of 5 square feet.

Treated plants are moved to the greenhouse and are left for 10 to 14days. The degree of growth response is determined by measuring threeparameters: total plant height, length of second node to appex, andpetiol length of the first trifoliate leaves.

A 0 to 9 scale reading is used to express the degree of growth response.A 0 scale reading in dicates growth retardation within the range of 0 to10 percent when compared with the control. A 9 scale reading correspondsto 90 percent or more growth retardation.

The particular active compounds tested, the concentration thereof usedand the results obtained can be seen from the following Table 2.

TABLE 2 provide the rates of application indicated below in PP Soybeanplants of the variety Clark 63 were used as test plants, and weresprayed with the particular active compound preparation at a rate of92.625 decalitres per hectare, at a time when less than 5 percent of theflowers were in bloom. The treatments were arranged by plots in arandomized block design and replicated 3 times. The control plotsreceived no treatment.

The degree of efficacy of the particular active compound was determinedby weighing the soybeans harvested from the treated and untreated plotsand expressing the results as a percentage of weight of treated toweight of untreated harvested soybeans. The plant height in the treatedplots, when compared with the untreated check plots, was also includedin the evaluation.

The particular active compound tested,.the rates of application and theresults obtained can be seen from the following Table 3.

P.p.m. Percent Solvent: 9.5 ml of water containing 0.01 percent byweight of polyoxyethylene sorbitan monolaurate (Tween 20) I To produce asuitable preparation of the particular active compound, 0.5 g of suchactive compound is Concentration (p.p.m.)

In this table, the letters A, B and C, refer respectively to total plantheight, length of second node to apex, and petiol length of the firsttrifoliate leaves.

EXAMPLE lll Soybean Yield Test Solvent: 9.5 ml. of water containing 0.01percent by weight of polyoxyethylene sorbitan monolaurate (Tween 20) Toproduce a suitable preparation of the particular active compound, 0.5 g.of such active compound is mixed with the stated amount of solvent, andthe resulting solution is then further diluted with such solvent tomixed with the stated amount of solvent, and the resulting solution isthen further diluted with such solvent to provide the rate ofapplication indicated below in ppm.

Plots of snap bean plants, when 5 to 10 percent of the flowers were inbloom, were sprayed with the particular active compound preparation at arate of 92.625 decaliters per hectare. The control plots received notreatment.

At harvest time the fresh weight of fruit from the treated and untreatedplots were determined. The yield of the treated plots was expressed as apercentage of the yield from the untreated control plots.

The particular active compound tested, the rate of application and theresults obtained can be seen from the following Table 4.

TABLE 4.-SNAPBEAN YIELD TEST Chemical Mowing of Kentucky BluegrassSolvent: 9.5 ml of water containing 0.01 percent by weight ofpolyoxyethylene sorbitan monolaurate (Tween 20) To produce a suitablepreparation of the particular active compound, 0.5 g of such activecompound is mixed with the stated amount of solvent, and the resultingsolution is then further diluted with such solvent to provide the ratesof application indicated below in pp Growing bluegrass sod was sprayedwith the particular active compound at the concentrations indicated.Plots were arranged in a randomized block design with 3 replications.The plots were mowed to a uniform height of 5 centimeters beforespraying, sprayed and then left for 5 weeks before readings were taken.

The degree of efficacy of the particular active compound was evaluatedby weighing a clipping from a 30 X 30 cm. area at a height of 2.45 cm.from the ground to determine the foliage yield from each plot.

The particular active compound tested, the rates of application and theresults obtained can be seen from the following Table 5.

TABLE 5.-CHElVllZCAL iatgiggi cgor KENTUCKY B11612- P.p.rn. of Averagefresh active green weight compound oi the c pp (a) Chemical Mowing ofKentucky Fescue Solvent: 9.5 ml of water containing 0.01 percent byweight of polyoxyethylene sorbitan monolaurate (Tween To produce asuitable preparation of the particular active compound, 0.5 g. of suchactive compound is mixed with the stated amount of solvent, and theresulting solution is then further diluted with such solvent to providethe rates of application indicated below in PP Growing fescue grass sodwas sprayed with the particular active compound at the concentrationsindicated. Plots were arranged in a randomized block design with threereplications. The plots were mowed to a uniform height of 5 centimetersbefore spraying,

sprayed and then left for 8 weeks before readings were taken.

The degree of efficacy of the particular active compound was evaluatedby weighing a clipping from a 30 X 30 cm. area at a height of 2.45 cm.from the ground to determine the foliage yield from each plot.

The particular active compound tested, the rates of application and theresults obtained can be seen from the following Table 6.

TABLE 6.CHEMICAL Mowiivo OF KENTUCKY FESCUE Average iresh Conccngreenwei ht trations of the c ip- Visual Compound (p.p.m.) ings (g) ratingsLCHzN C S 0 Same as above 1,000 85. 3 10 Control 0 103. 2 0

EXAMPLE Vll Chemical Pruning of Elm Trees Solvent: 9.5 ml of watercontaining 0.01 percent by weight of polyoxyethylene sorbitanmonolaurate (Tween 20) To produce a suitable preparation of theparticular active compound, 0.5 g. of such active compound is mixed withthe stated amount of solvent, and the resulting solution is then furtherdiluted with such solvent to provide the rates of application indicatedbelow in ppm. Thispreparation of the mixture of the particular activecompound with maleic hydrazide (Mil-30) was made by mixing together onepart by weight of the given active compound and 3 parts by weight ofmaleic hydrazide, mixing 0.5 g. of the resulting mixture with the statedamount of solvent, and then further diluting it with such solvent toprovide the rates of application I indicated below in ppm.

3-year-old American Elm trees were used as test plants. The treatmentswere applied on 2 limbs per tree and replicated 3 times. The retardationof twig growth was determined by measuring the length of a twig 17 weeksafter treatment and comparing it to the length of the same twig beforetreatment. The average difference in growth between each of the sixtreated limbs and six untreated control limbs is calculated as apercentage of the average growth of the control limbs, and the resultexpressed as percent inhibition of growth of the untreated twigs.

The particular active compound tested, the rates of application and theresults obtained can be seen from the following Table 7.

TABLE 7.-CIIEMICAL PRUNING 0F ELM TREES Total Percentage p.p.m.oiinhibition EXAMPLE VIII Peach Fruit Thinning Test Solvent: 9.5 ml ofwater containing 0.01 percent by weight of polyoxyethylene sorbitanmonolaurate (Tween 20) To produce a suitable preparation of theparticular active compound, 0.5 g. of such active compound is mixed withthe stated amount of solvent, and the resulting solution is then furtherdiluted with such solvent to provide the rates of application indicatedbelow in PP Ten-year-old Redhaven peach trees were used as test plants,and single limbs of these trees were sprayed with the given activecompound preparation at a rate of 277.785 decaliters per hectare 5 daysafter full bloom. Each treatment was replicated 3 times and eachreplicate was on separate trees. The control plots received notreatment.

The degree of efficacy of the particular active compound was determinedby comparing the number of fruit blossoms remaining on the treated limbsat hand thinning time with the number of flowers per untreated limb, itbeing known that a tree will bear larger fruit where there are fewertotal fruit to be supported. It is also known that thinning the fruitfrom a tree one can affect the alternate bearing habits of the fruittrees to give a more consistent yield year after year rather thanalternating heavy and little or no yield of fruit in alternate years.

The particular active compound tested, the rates of application and theresults obtained can be seen from the following Table 8.

TABLE 8.-PEACH FRUIT-THINNING TEST P.p.m. of

active Percent fruit compound thlnnlngover The following furtherexamples and Table of Compounds illustrate, without limitation, a numberof heterocylic alkyl isothiocyanates usable in accordance with thepresent invention.

EXAMPLE 1X A mixture of 50 g. (0.515 mole) of furfuryl amine and 50 g.(0.5 mole) triethyl amine was dissolved in 70 ml. of dioxane and cooledto C. To this mixture was added 40 g. (0.525 mole) of carbon disulfideand the reaction mixture was allowed to warm to room temperature. Ethylchloroformate, 57 g. (0.53 mole), was added dropwise followed by theaddition of 200 ml. of chloroform and an additional 50 g. (0.5 mole) oftriethylamine. The reaction mixture was stirred at room temperature for60 hours, the solid was filtered and the organic solution was washedwith water. After evaporation of the solvent, the residue was dried byazeotroping with benzene. Distillation gave 19 g. of colorless liquid.b.p. 5254C (0.9mm). Calc. for C, 51.8; H, 4.3; N, 10.l;found,C, 51.8; H,3.9; N, 10.0.

The reactions involved are as follows:

Step I 0 ll \0 -oinr-uicscoonn (CgllmN-llCl Step II S l n nOJCH2NIICSCOCzHa (CzHali In the corresponding manner there are obtained:

Compound Physical properties (1) 61 C. (0.5mn1.).

i l -CH2NC S (3) 63 C.(0.3 mm.).

I GH:NC S

(4) 112 C. (1.5 mm.).

CH NC S (4) 93 C. (0.45 mm.).

\ -omcirmos EXAMPLE X (J) i j pmcrnn 0 (JHNC 3 To a solution of 27 g.(0.193 mole) of a-isopropyl 2- furyl carbinol in ml. of pyridine wasadded with cooling 22 g. (0.193 mole) of methane sulfonyl chloride overa one hour period. After standing overnight, the solid mass was dried inan oven at 50C and dissolved in 60 mls. of acetone. To this solution wasadded 30 g. (0.3 mole) of potassium thiocyanate and the reaction mixturewas refluxed for 3 hours. After filtration and removal of the solvent byevaporation, the resultant oil was extracted with 500 mls. of methylenechloride, washed with water, dried over anhydrous magnesium sulfate andfiltered. Removal of the solvent by evaporation, left 30 g of residualoil which was twice distilled to give 6 g. (17 percent ofa-isopropyl-Z-furfuryl isothiocyanate, pale yellow liquid distilling at48C (0.07 mm).

The reactions involved are as follows:

J tlnuom 2 \O CllNCS EXAMPLE Xl To a solution of 19.4 g. (0.2 mole) ofpotassium thiocyanate in 250 ml of acetone was added 19.9 g. (0.15 mole)of 2-thenyl chloride. After the addition was complete, the mixture washeated under reflux for 1 hour and allowed to cool at room temperature.The acetone was removed under reduced pressure and the residue wasdissolved in a mixture of methylene chloride and water. The methylenechloride layer was separated and was dried over sodium sulfate. A yellowoil was obtained on distillation of the dried organic layer.Distillation of this oil gave 19.7 grams of 2-thenyl thiocyanate (87percent) boiling at 77C(0.05 mm), n 1.5984.

In the corresponding manner there are obtained:

(14) T CHzSCN Brl J-Br S EXAMPLE Xll B.p. 58 C.(0.05) mm.

A mixture of 12.8 grams (0.08 mole) of Z-thenyl thiocyanate and 0.5 gramof zinc chloride in 25 mls. of

Physical Properties B.p. 82 C.(0.05 mn1.).

Compound (8) B.p. 9296 C.(0.04 mm).

(26) B.p. C. (0.03 111111.).

CHzNCS It will be realized by the artisan that all of the foregoingcompounds contemplated by the present invention possess some degree ofgrowth regulating properties. It will be further appreciated that theinstant specification examples are set forth by the way of illustrationand not limitation, and that various modifications and changes may bemade without departing from the spirit and scope of the presentinvention which is to be limited only by the scope of the appendedclaims.

What is claimed is:

1. The method of retarding the growth of plants which comprises applyingto such plants a growth retarding amount of a compound of the formula:

formula:

L J-CIhNCS 4. Method according to claim ll wherein such compound is:Z-furfuryl isothiocyanate of the formula:

2. Method according to claim 1 wherein Z is furyl or pyranyl as well asdi- and tetra-hydrogenated derivatives thereof, optionally substitutedwith chlorine or bromine.
 3. Method according to claim 1 wherein suchcompound is: 2-tetrahydrofurfuryl isothiocyanate of the formula: 4.Method according to claim 1 wherein such compound is: 2-furfurylisothiocyanate of the formula:
 5. Method according to claim 1 whereinsuch compound is: 2-Isothiocyanato-3,4-dihydro-2H-pyran of the formula: